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Tsirkin" , =?utf-8?q?Alex_Benn=C3=A9e?= , Dmitry Osipenko Subject: [PATCH 2/2] hw/display: check frame buffer can hold blob Date: Mon, 4 Nov 2024 16:53:48 +0000 Message-Id: <20241104165348.2361299-3-alex.bennee@linaro.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20241104165348.2361299-1-alex.bennee@linaro.org> References: <20241104165348.2361299-1-alex.bennee@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::62a; envelope-from=alex.bennee@linaro.org; helo=mail-ej1-x62a.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Coverity reports (CID 1564769, 1564770) that we potentially overflow by doing some 32x32 multiplies for something that ends up in a 64 bit value. Fix this by casting the first input to uint64_t to ensure a 64 bit multiply is used. While we are at it note why we split the calculation into stride and bytes_pp parts. Signed-off-by: Alex Bennée Cc: Dmitry Osipenko --- hw/display/virtio-gpu.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c index e7ca8fd1cf..572e4d92c6 100644 --- a/hw/display/virtio-gpu.c +++ b/hw/display/virtio-gpu.c @@ -741,9 +741,14 @@ bool virtio_gpu_scanout_blob_to_fb(struct virtio_gpu_framebuffer *fb, fb->stride = ss->strides[0]; fb->offset = ss->offsets[0] + ss->r.x * fb->bytes_pp + ss->r.y * fb->stride; + /* + * We calculate fb->stride for every line but the last which we + * calculate purely by its width. The stride will often be larger + * than width to meet alignment requirements. + */ fbend = fb->offset; - fbend += fb->stride * (ss->r.height - 1); - fbend += fb->bytes_pp * ss->r.width; + fbend += (uint64_t) fb->stride * (ss->r.height - 1); + fbend += (uint64_t) fb->bytes_pp * ss->r.width; if (fbend > blob_size) { qemu_log_mask(LOG_GUEST_ERROR,